struct TIME {

    static var ti = mach_timebase_info()
    static var k: Double = 1
    static var mach_stamp: Double {

        if ti.denom == 0 {
            mach_timebase_info(&ti)
            k = Double(ti.numer) / Double(ti.denom) * 1e-6
        }
        return Double(mach_absolute_time()) * k
    }
    static var stamp: Double { return NSDate.timeIntervalSinceReferenceDate() * 1000 }
}

do {
    let mach_start = TIME.mach_stamp
    usleep(200000)
    let mach_diff = TIME.mach_stamp - mach_start

    let start = TIME.stamp
    usleep(200000)
    let diff = TIME.stamp - start

    print(mach_diff, diff)
}

既然你想优化时间从一个页面移动到另一个UIWebView，这是不是意味着你真的在寻找优化Javascript加载这些页面?

为此，我想看看WebKit分析器，就像这里所说的:

http://www.alertdebugging.com/2009/04/29/building-a-better-javascript-profiler-with-webkit/

另一种方法是从高层次开始，思考如何设计有问题的网页，使用AJAX样式的页面加载来最小化加载时间，而不是每次都刷新整个web视图。

一个在Swift 4中使用mach_absolute_time()的细粒度计时的例子:

let start = mach_absolute_time()

// do something

let elapsedMTU = mach_absolute_time() - start
var timebase = mach_timebase_info()
if mach_timebase_info(&timebase) == 0 {
    let elapsed = Double(elapsedMTU) * Double(timebase.numer) / Double(timebase.denom)
    print("render took \(elapsed)")
}
else {
    print("timebase error")
}

下面是我使用的两个单行宏:

#define TICK   NSDate *startTime = [NSDate date]
#define TOCK   NSLog(@"Time: %f", -[startTime timeIntervalSinceNow])

像这样使用它:

TICK;

/* ... Do Some Work Here ... */

TOCK;

这里有一个Swift 3的解决方案，可以在任何地方对代码进行等分，以找到长时间运行的进程。

var increment: Int = 0

var incrementTime = NSDate()

struct Instrumentation {
    var title: String
    var point: Int
    var elapsedTime: Double

    init(_ title: String, _ point: Int, _ elapsedTime: Double) {
        self.title = title
        self.point = point
        self.elapsedTime = elapsedTime
    }
}

var elapsedTimes = [Instrumentation]()

func instrument(_ title: String) {
    increment += 1
    let incrementedTime = -incrementTime.timeIntervalSinceNow
    let newPoint = Instrumentation(title, increment, incrementedTime)
    elapsedTimes.append(newPoint)
    incrementTime = NSDate()
}

用法:-

instrument("View Did Appear")

print("ELAPSED TIMES \(elapsedTimes)")

样例输出:

[MyApp.SomeViewController.]仪器仪表(标题:“开始视图 Did Load"， point: 1, elapsedTime: 0.040504038333892822)， MyApp.SomeViewController。检测(标题:“完成添加 SubViews"， point: 2, elapsedTime: 0.010585010051727295)， MyApp.SomeViewController。仪器仪表(标题:“视图已出现”， 点:3,elapsedTime: 0.56564098596572876)]

对于Swift 4，添加一个委托到你的类:

public protocol TimingDelegate: class {
    var _TICK: Date?{ get set }
}

extension TimingDelegate {
    var TICK: Date {
        _TICK = Date()
        return(_TICK)!
     }

    func TOCK(message: String)  {

        if (_TICK == nil){
            print("Call 'TICK' first!")
        }

        if (message == ""){
            print("\(Date().timeIntervalSince(_TICK!))")
        }
        else{
            print("\(message): \(Date().timeIntervalSince(_TICK!))")
        }
    }
}

加入我们班:

class MyViewcontroller: UIViewController, TimingDelegate

然后添加到你的类:

var _TICK: Date?

当你想为某事计时时，可以从以下开始:

TICK

最后:

TOCK("Timing the XXX routine")